Muhammad Jawad Asghar

Field Evaluation of Mungbean Recombinant Inbred Lines against Mungbean Yellow Mosaic Disease Using New Disease Scale in Thailand

Studies were conducted to identify the sources of resistance in mungbean recombinant inbred lines (RILs) in Thailand against mungbean yellow mosaic disease (MYMD). 146 mungbean RILs in series were evaluated in a field including resistant parent NM-10-12-1 and susceptible parent KPS 2 during summer 2008 under high inoculum pressure. The RILs were subsequently scored for disease symptom severity ratings (DSSR) using a new scale. Observations regarding DSSR and % disease index (%DI) showed that the tested RILs responded differently to the disease. A large number of RILs (132) were found highly susceptible, 12 were susceptible, 3 were tolerant and one was resistant. Overall screening results showed that three RILs, viz. line no. 30, 100 and 101 had minimum DSSR and % disease index thus they are good source of resistance to MYMD in spite of high disease pressure and can therefore be used directly as varieties to manage the disease in Thailand.

Occurrence of Cucumber mosaic virus Subgroup IA in tomato in Pakistan

Infection of tomato in Faisalabad, Pakistan with subgroup IA strain of Cucumber mosaic virus (CMV) is reported for the first time. The virus was detected by Rt-PCR using genus-specific single pair of primers and was transmitted by Myzus persicae in the non-persistent manner.ZusammenfassungMit der Untergruppe IA des Gurkenmosaikvirus infizierte Tomaten wurden erstmals in Pakistan nachgewiesen. Das Virus wurde mit einem einzelnen genusspezifischen Primer-paar mittels RT-PCR nachgewiesen. Die Übertragung durch Myzus persicae erfolgte nicht-persistent.

Genetic Confirmation of Mungbean (Vigna radiata) and Mashbean (Vigna mungo) Interspecific Recombinants using Molecular Markers

Molecular confirmation of interspecific recombinants is essential to overcome the issues like self-pollination, environmental influence, and inadequacy of morphological characteristics during interspecific hybridization. The present study was conducted for genetic confirmation of mungbean (female) and mashbean (male) interspecific crosses using molecular markers. Initially, polymorphic random amplified polymorphic DNA (RAPD), universal rice primers (URP), and simple sequence repeats (SSR) markers differentiating parent genotypes were identified. Recombination in hybrids was confirmed using these polymorphic DNA markers. The NM 2006 × Mash 88 was most successful interspecific cross. Most of true recombinants confirmed by molecular markers were from this cross combination. SSR markers were efficient in detecting genetic variability and recombination with reference to specific chromosomes and particular loci. SSR (RIS) and RAPD identified variability dispersed throughout the genome. In conclusion, DNA based marker assisted selection (MAS) efficiently confirmed the interspecific recombinants. The results provided evidence that MAS can enhance the authenticity of selection in mungbean improvement program.

Mungbean phyllody disease in Pakistan: symptomatology, transmission, varietal response and effects on yield characteristics

Mungbean plants showing typical symptoms of infection by a phytoplasma that causes phyllody disease (transformation of floral parts into green, leaf-like structures) were examined in field crops in both spring and summer seasons. The most common symptoms were floral virescence, phyllody, reduction in leaf size, extensive proliferation of branches and stunting of plants. Sometimes these symptoms were accompanied by longitudinal splitting of green pods followed by germination of green (physiologically mature) seeds, producing small plants. Phyllody disease pathogen was successfully transmitted from diseased to healthy mungbean plants using either grafting and the leafhopper Orosius albicinctus under laboratory conditions. Transmission via seeds and by insects that included leafhopper Amrasca devastans, pea aphid Acyrthosiphon pisum, beetles Brumoides suturalis, Hippodamia variegata, Menochilus sexmaculatus, and the whitefly Bemisia tabaci failed to produce disease under laboratory conditions. During the spring and summer seasons of 2009, a field trial of 162 exotic and indigenous mungbean genotypes obtained from 8 different geographical regions was conducted, aiming to shed light on the causes of susceptibility to phyllody disease. Sixty-one genotypes showed infection, ranging from 1.00% to 4.35%. Significant variation in all yield and morphological characteristics due to phyllody disease on mungbean plants depending on growth stages was also recorded. Comparison between healthy and diseased plants showed significant percentage reduction at all growth stages. Maximum reduction in all the tested charcateristics was recorded when plants were infected before flowering followed by infection at the flowering and pod-setting stages. The most severely affected plant variables at all infection stages were the number of seeds per plant, the number of normal seeds per plant and yield per plant. Severely infected plants produced no seeds but some partially infected plants produced very small, sickle-shaped, upright and leathery pods with degenerate seeds.

Effect of cucumber mosaic virus infection on morphology, yield and phenolic contents of tomato

Ten tomato genotypes were screened for their resistance against cucumber mosaic virus (CMV) and its vector Myzus persicae under natural infection in field, using aphids M. persicae under net-house and mechanical inoculation under greenhouse. Large differences were observed among genotypes for infection percentage (IP) and severity index (SI) among the testing methods used. All genotypes showing tolerance to CMV in the field or through aphid inoculation, however, become susceptible and highly susceptible after mechanical inoculation. All the test genotypes also showed susceptibility to the aphid M. persicae population. Plants inoculated with CMV showed substantial decrease in yield and yield-contributing parameters which varied with cultivars that probably depended upon its genetic make up. All the test genotypes exhibited 0.97–30.19% decrease in plant height, 11.47–52.65% decrease in root length, 46.56–95.56% decrease in fresh plant weight, 65.78–92.84% decrease in root fresh weight, 19.97–87.65% decrease in the dry weight of plants, 75.63–95.43% decrease in dry root weight, 69.51–95.65% reduction in the number of fruits and 89.04–99.89% decrease in yield per plants. After 15 days of inoculation, the quantitative analysis using double beam spectrophotometer showed an increase in total phenolics in CMV-inoculated plants as compared to un-inoculated plants among genotypes. Similarly the thin layer chromatography (TLC) on silica gel G indicated that the number of phenolic compounds was increased in most of the inoculated genotypes while in others they were either decreased or remained same.

EVALUATION OF TOMATO GENOTYPES FOR LATE BLIGHT RESISTANCE USING LOW TUNNEL ASSAY

Late blight (LB) caused by Phytophthora infestans is one of the major bottlenecks of low productivity of tomato worldwide including Pakistan. Transfer of resistance into elite lines is the principal way to combat this problem. However, lack of reliable methods to screen and evaluate plant resistance prior to breeding has been a limiting factor in the development of tomato varieties resistant to LB. In the present study, we screened 285 tomato genotypes of diverse genetic pool using a low tunnel assay for the first time to the best of our knowledge and confirmed that it is not an established method in use for the same purpose. Results over the multiyear (2013-2015) elucidated one resistant genotype LO6122 (Solanum arcanum) and 31 moderately resistant genotypes (one of S. arcanum and 30 of S. lycopersicum) to LB. Rest of the genotypes including mutants and differential plants having major LB resistant genes (Ph1, Ph2, Ph3 and Ph2 + Ph3) were ranged from susceptible to highly susceptible. Strong resistance conferred by LO6122 points out the presence of an alternate source of genes resistant to LB. Therefore, this line can possibly be used as a donor parent of resistance against virulent strains of P. infestans. This study also showed that low tunnel assay is practicable, efficient, simple, and cost effective in terms of space and pathogen inoculum required. It gives high output results to distinguish resistant and susceptible genotypes even when screening of large number of genotypes and breeding populations against LB is exercised.

Convolvulus arvensis, a new host for Alternaria solani causing early blight of Solanum lycopersicum in Pakistan

In March–April 2011, a severe outbreak of early blight disease caused by Alternaria solani was observed on Solanum lycopersicum (cultivated tomatoes) at the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan. A similar type of symptoms was also observed on Convolvulus arvensis (field bindweed, lehli). Based on disease symptoms, morphological characteristics and pathogenicity test, it has been confirmed that the A. solani could infect C. arvensis. To the best of our knowledge this is the first report of A. solani infecting C. arvensis in Pakistan.

Pre-breeding of lentil (Lens culinaris Medik.) for herbicide resistance through seed mutagenesis

Lentil is a poor competitor of weeds and its sensitivity to herbicides is a major hurdle for large scale production. The present study was conducted to select herbicide resistant lentil genotypes through seed mutagenesis. Seeds of three advanced lentil genotypes (LPP 11001, LPP 11100 and LPP 11116) were treated with two different concentrations of ethyl methanesulfonate (EMS; 0.1 and 0.2%), hydrazine hydrate (HH; 0.02 and 0.03%) and sodium azide (SA; 0.01 and 0.02%) to develop M1 seed. The M2 was screened against two herbicides including Ally Max 28.6% SG (X = 34.58 g/ha and 1.5X = 51.87 g/ha) and Atlantis 3.6% WG (X = 395.2 g/ha and 1.5X = 592.8 g/ha) using the following three screening methods: post plant emergence (PPE), pre-plant incorporation (PPI) and seed priming (SP). Data were recorded on survival index and survival percentage from each experimental unit of every population. Plants in all populations were categorized following their reaction to herbicides. The newly developed populations showed greater variation for herbicide resistance when compared to their progenitors. Phenotypic traits were significantly reduced in all the screening environments. Overall, 671 herbicide resistant mutants were selected from all testing environments. The seeds from selected plants were re-mutagenized at 150 Gy of gamma radiation and evaluated against higher dose of herbicides. This allowed selection of 134 herbicide resistant mutants. The selected mutants are useful germplasm for herbicide resistance breeding of lentil.

Time-course analysis of the phenols in cucumber mosaic virus-resistant, -tolerant and -susceptible tomato genotypes

In this study, changes in quantity and quality of phenolic compounds were compared in cucumber mosaic virus (CMV)-inoculated and -un-inoculated plants of nine resistant, tolerant, susceptible and highly susceptible genotypes at three different time intervals. Total phenolic contents and the number of phenolic compounds were generally increased in CMV-inoculated plants. Maximum per cent increase in total phenolic contents over un-inoculated controls was observed as 77.55% in resistant genotype TMS-1, 84.17% in tolerant genotype L06238 and 82.88% in resistant genotype L02223 after 10, 20 and 30 days of inoculation, respectively. Thin layer chromatography of inoculated and un-inoculated plants indicates that in most of the tested genotypes, the number of phenolic compounds varied from cultivar to cultivar and within the same cultivar, depending upon the status of plants and growth stages. However, the trend of increase in quantity and quality of phenolic compounds in the tested units was not constant to draw a meaningful conclusion.

Mapping of esterase loci in Aegilops uniaristata and homoeologous group 3 chromosomes of wheat

This study was planned to identify the chromosomal location of esterase loci in wheat (Triticum aestivum), in comparison to Aegilops uniaristata, using wheat Ae. uniaristata disomic addition and translocation lines. Two loci (Est-N1 and Est-N8) were identified on 3N chromosome of Ae. uniaristata and their probable homoeoloci were, for the first time, mapped close to three RFLP probes (Xpsr56, Xpsr394, and Xpsr1196) on homoeologous group 3 wheat chromosomes.